Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 514 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.815 − 798 =
2. 2.325 − 297 =
3. 3.478 − 459 =
4. 4.896 − 499 =
5. 5.830 − 797 =
6. 6.818 − 527 =
7. 7.974 − 799 =
8. 8.550 − 198 =
9. 9.733 − 197 =
10. 10.207 − 188 =
11. 11.799 − 348 =
12. 12.350 − 208 =
13. 13.579 − 199 =
14. 14.714 − 169 =
15. 15.893 − 179 =
16. 16.721 − 299 =
17. 17.972 − 397 =
18. 18.974 − 269 =
19. 19.863 − 799 =
20. 20.810 − 277 =
21. 21.521 − 367 =
22. 22.842 − 299 =
23. 23.862 − 209 =
24. 24.705 − 249 =
25. 25.664 − 199 =
26. 26.668 − 598 =
27. 27.371 − 348 =
28. 28.452 − 319 =
29. 29.684 − 598 =
30. 30.980 − 538 =
31. 31.421 − 399 =
32. 32.870 − 498 =
33. 33.853 − 197 =
34. 34.826 − 557 =
35. 35.900 − 798 =
36. 36.713 − 197 =
37. 37.924 − 509 =
38. 38.679 − 599 =
39. 39.571 − 498 =
40. 40.733 − 638 =

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